Versatile cryogen-free cryostat for the electromagnetic characterization of superconducting radiofrequency coils

Saniour, Isabelle; Geahel, Michel; Briático, J.; Beek, C. J. van der; Willoquet, Georges; Jourdain, Laurène; Baudouy, Bertrand; Authelet, G.; Ginefri, Jean-Christophe; Darrasse, Luc; Poirier‐Quinot, Marie

doi:10.1140/epjti/s40485-020-00055-2

Cited by 2 publications

(2 citation statements)

References 29 publications

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“…Saniour et al [ 64 ] presented a cryogenic free cryostat design to characterize the RF properties of a HTS. The vacuum chamber was a sealed in a four-way cross with a cold head installed at the bottom of the cross, and the coil being tested was placed inside the vacuum chamber at the top of the cross.…”

Section: Strategies For Minimizing the Conductor Lossesmentioning

confidence: 99%

Conductor Losses in Radiofrequency Coils for Magnetic Resonance below 3T: Estimation Methods and Minimization Strategies

Giovannetti

Flori

Frijia

2023

Sensors

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The design of optimized radiofrequency (RF) coils is a fundamental task for maximizing the signal-to-noise ratio (SNR) in Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) applications. An efficient coil should be designed by minimizing the coil noise with respect to the sample noise, since coil conductor resistance affects data quality by reducing the SNR, especially for coils tuned to a low frequency. Such conductor losses strongly depend on the frequency (due to the skin effect) and on the conductor cross-sectional shape (strip or wire). This paper reviews the different methods for estimating conductor losses in RF coils for MRI/MRS applications, comprising analytical formulations, theoretical/experimental hybrid approaches and full-wave simulations. Moreover, the different strategies for minimizing such losses, including the use of Litz wire, cooled and superconducting coils, are described. Finally, recent emerging technologies in RF coil design are briefly reviewed.

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Section: Strategies For Minimizing the Conductor Lossesmentioning

confidence: 99%

Conductor Losses in Radiofrequency Coils for Magnetic Resonance below 3T: Estimation Methods and Minimization Strategies

Giovannetti

Flori

Frijia

2023

Sensors

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“…Setup 1-The HTS surface coil is used in a dedicated cryostat [50] shown schematically in Figure 4, cooled in Earth's magnetic field and characterized with a VNA and a method inspired from [47]. The electrical parameters of the HTS coil are obtained through the measurement of its RF response using an inductive coupling approach involving a measurement probe overcoupled with the HTS coil.…”

Section: Decoupling the High-temperature Superconducting Coil During Transmissionmentioning

confidence: 99%

Recent Advances and Challenges in the Development of Radiofrequency HTS Coil for MRI

et al. 2021

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Radiofrequency (RF) coils fashioned from high-temperature superconductor (HTS) have the potential to increase the sensitivity of the magnetic resonance imaging (MRI) experiment by more than a dozen times compared to conventional copper coils. Progress, however, has been slow due to a series of technological hurdles. In this article, we present the developments that recently led to new perspectives for HTS coil in MRI, and challenges that still need to be solved. First, we recall the motivations for the implementations of HTS coils in MRI by presenting the limits of cooled copper coil technology, such as the anomalous skin effect limiting the decrease of the electric resistance of normal conductors at low temperature. Then, we address the progress made in the development of MRI compatible cryostats. New commercially available low-noise pulsed-tube cryocoolers and new materials removed the need for liquid nitrogen-based systems, allowing the design of cryogen-free and more user-friendly cryostats. Another recent advance was the understanding of how to mitigate the imaging artifacts induced by HTS diamagnetism through field cooling or temperature control of the HTS coil. Furthermore, artifacts can also originate from the RF field coupling between the transmission coil and the HTS reception coil. Here, we present the results of an experiment implementing a decoupling strategy exploiting nonlinearities in the electric response of HTS materials. Finally, we discuss the potential applications of HTS coils in bio-imaging and its prospects for further improvements. These include making the technology more user-friendly, implementing the HTS coils as coil arrays, and proposing solutions for the ongoing issue of decoupling. HTS coil still faces several challenges ahead, but the significant increase in sensitivity it offers lends it the prospect of being ultimately disruptive.

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Versatile cryogen-free cryostat for the electromagnetic characterization of superconducting radiofrequency coils

Cited by 2 publications

References 29 publications

Conductor Losses in Radiofrequency Coils for Magnetic Resonance below 3T: Estimation Methods and Minimization Strategies

Conductor Losses in Radiofrequency Coils for Magnetic Resonance below 3T: Estimation Methods and Minimization Strategies

Recent Advances and Challenges in the Development of Radiofrequency HTS Coil for MRI

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